Don't look a gift horse in the mouth Informal

Do not criticize, question, or find fault with something that is given to you for free.

The advice is about gratitude and grace, not honesty — even an imperfect gift is treated as something to accept politely rather than evaluate as if it were a purchase.

This is one of the oldest documented proverbs still in everyday use: St. Jerome quoted it as already proverbial in his “Commentary on the Epistle to the Ephesians” around 387-388 CE, in the Latin form “equi dentes inspicere donati” (don’t inspect the teeth of a given horse). It entered English well over a thousand years later — an early version appears around 1510 in the schoolbook “Vulgaria Stambrigi” as “A gyven hors may not be loked in the tethe,” and John Heywood recorded a close variant in his 1546 proverb collection. Desiderius Erasmus discussed the saying at length in his 1508 “Adagia,” specifically framing it as a rebuke to people who criticize what’s freely given to them. The literal logic is straightforward: a horse’s age and health can be judged by examining the wear on its teeth, so checking a gift horse’s mouth would mean assessing its value as though it had been bought rather than received.

He complained about the color of the free laptop his company gave him — talk about looking a gift horse in the mouth.

It’s a used car, but it runs fine, so don’t look a gift horse in the mouth.

I know the internship isn’t paid, but don’t look a gift horse in the mouth — it’s great experience.

A: “The hand-me-down couch has a small stain.” B: “Don’t look a gift horse in the mouth, at least we got a free couch.”